Power transmission apparatus for a vehicle

ABSTRACT

A power transmission apparatus for a vehicle may include: first, second, and third input shafts disposed coaxially with each other and each selectively connected with a motor/generator; a torque mediating shaft disposed coaxially with the first input shaft; a first intermediate shaft in parallel with the first input shaft; a second intermediate shaft in parallel with the first input shaft, and selectively connected with a transmission housing; a first shifting section including five gear sets, selectively receiving torques through the first and third input shafts, and providing intermediate shift-stages; and a second shifting section including a planetary gear set, forming an output torque by combination of torques from the first shifting section and the second input shaft, and outputting the output torque to the output shaft through one gear set.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2018-0091541, filed on Aug. 7, 2018, the entirecontents of which are incorporated herein by reference.

FIELD

The present disclosure relates to a power transmission apparatus for avehicle.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

An environmentally-friendly technology of a vehicle is a core technologywhich controls survival of a future automobile industry, and advancedcar makers have focused on the development of anenvironmentally-friendly vehicle to comply with regulations forenvironment and fuel efficiency.

An electric vehicle (EV) or a hybrid electric vehicle (HEV) thatutilizes electrical energy, or a double clutch transmission (DCT)improving efficiency and convenience of a transmission may be examplesof such future vehicle technology.

The double clutch transmission (DCT) includes two clutches devices and agear train of a basically manual transmission, selectively transmits atorque input from an engine to two input shafts by using the twoclutches devices, and outputs a torque shifted by the gear train.

Such a double clutch transmission (DCT) attempts to compactly realize amulti-stage transmission of more than five speeds. The DCT achieves anautomated manual transmission (AMT) that removes the inconvenience of amanual shifting of a driver, by controlling two clutches andsynchronizing devices by a controller.

In comparison with an automatic transmission using planetary gears, sucha DCT shows merits, such as higher efficiency in power delivery, easiermodification in revising or adding parts in order to achieve moreshift-stages, etc., and thus gathers more spotlight since it can morecomfortably conform to fuel consumption regulations and efficiency inachieving more shift-stages.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the present disclosureand therefore it may contain information that does not form the priorart that is already known to a person of ordinary skill in the art.

SUMMARY

The present disclosure provides a power transmission apparatus for avehicle having an advantage of achieving shift-stages in an electricvehicle mode and in a parallel hybrid mode by employing a simplearrangement of a planetary gear set and a motor/generator to a doubleclutch scheme, thereby improving fuel consumption and betterapplicability to a hybrid vehicle.

An exemplary power transmission apparatus is for a vehicle having anengine and a motor/generator. The power transmission apparatus mayinclude: a first input, a second input shaft, a third input shaft, atorque mediating shaft, a first intermediate shaft, a secondintermediate shaft, a first shifting section, a second shifting section,and an output shaft. The first input shaft may be selectively connectedwith the motor/generator. The second input shaft may be formed as ahollow shaft, disposed coaxial with and external to the first inputshaft without rotational interference, and selectively connected withthe motor/generator. The third input shaft may be formed as a hollowshaft, disposed coaxial with and external to the second input shaftwithout rotational interference, and selectively connected with themotor/generator. The torque mediating shaft may be formed as a hollowshaft disposed coaxial with and external to the first input shaftwithout rotational interference. The first intermediate shaft may bedisposed in parallel with the first input shaft. The second intermediateshaft may be disposed in parallel with the first input shaft, andselectively connected with a transmission housing. The first shiftingsection may include five gear sets (i.e., a first gear set, a secondgear set, a third gear set, a fourth gear set, and a fifth gear set)disposed on the first and third input shafts, the first and secondintermediate shafts, and the torque mediating shaft. The first shiftingsection may selectively receive torque through the first and third inputshafts and provide a plurality of intermediate shift-stages shifted fromthe received torque. The second shifting section may include a planetarygear set having a sun gear fixedly connected with the torque mediatingshaft, form an output torque by combination of a torque selectivelytransmitted from the first shifting section and a torque selectivelyinput through the second input shaft, and output the output torque tothe output shaft through the one gear set selected among the first,second, third, fourth and fifth gear sets of the first shifting section.The output shaft may be disposed coaxially with and selectivelyconnected with the second intermediate shaft and output a torquereceived from the first and second shifting sections.

The first gear set may include a first drive gear fixedly connected withthe third input shaft and a first driven gear fixedly connected with thefirst intermediate shaft and externally gear-meshed with the first drivegear. The second gear set may include a second drive gear disposedcoaxial with and external to the first intermediate shaft withoutrotational interference, an intermediate gear fixedly connected with thetorque mediating shaft and externally gear-meshed with the second drivegear, and a second driven gear fixedly connected with the secondintermediate shaft and externally gear-meshed with the intermediategear. The third gear set may include a third drive gear fixedlyconnected with the first input shaft, and a third driven gear rotatablydisposed on an external circumference of the second intermediate shaftwithout rotational interference and externally gear-meshed with thethird drive gear. The fourth gear set may include a fourth drive gearfixedly connected with the first input shaft, and a fourth driven gearrotatably disposed on an external circumference of the secondintermediate shaft without rotational interference and externallygear-meshed with the fourth drive gear. The fifth gear set may include afifth drive gear disposed coaxial with and external to the firstintermediate shaft without rotational interference, and a fifth drivengear fixedly connected with the second intermediate shaft and externallygear-meshed with the fifth drive gear.

The third driven gear and the fourth driven gear are selectivelyconnected with the second intermediate shaft through a firstsynchronizer; and

The second drive gear and the fifth drive gear are selectively connectedwith the first intermediate shaft through a second synchronizer.

Gear ratios of the first gear set and the second gear set may be usedfor realizing the forward second speed and the forward sixth speed. Agear ratio of the third gear set may be used for realizing the forwardfirst speed and the forward seventh speed. A gear ratio of the fourthgear set may be used for realizing the forward third speed and theforward fifth speed. A gear ratio of the fifth gear set may be used forrealizing the forward ninth speed and the reverse speed in cooperationwith the gear ratio of the first gear set.

A sun gear of the planetary gear set may be fixedly connected with thetorque mediating shaft. A planet carrier of the planetary gear set maybe fixedly connected with the second input shaft. A ring gear of theplanetary gear set may be externally gear-meshed with the output shaftthrough the sixth gear set.

The sixth gear set may include a sixth drive gear fixedly connected withthe ring gear of the planetary gear set, and a sixth driven gear fixedlyconnected with the output shaft and externally gear-meshed with thesixth drive gear.

The planetary gear set may be a single pinion planetary gear set.

The power transmission apparatus may further include five clutches eachselectively connecting a corresponding pair among the first, second andthird input shafts, the torque mediating shaft, and the first and secondintermediate shafts, and a brake selectively connecting a correspondingshaft selected among the first, second and third input shafts, thetorque mediating shaft, and the first and second intermediate shafts tothe transmission housing.

The five clutches may include an engine clutch arranged between anengine output shaft of the engine and a motor shaft of themotor/generator, a first clutch arranged between the motor shaft and thefirst input shaft, a second clutch arranged between the motor shaft andthe second input shaft, a third clutch arranged between the motor shaftand the third input shaft, and a fourth clutch arranged between thesecond intermediate shaft and the output shaft. The brake may bearranged between the second intermediate shaft and the transmissionhousing.

The first and second shifting sections may be disposed in the order ofthe second shifting section and the first shifting section from theengine.

A power transmission apparatus for a vehicle according to an exemplaryform of the present disclosure realizes shift-stages of nine forwardspeeds and one reverse speed by employing a planetary gear set and twosynchronizers to a multiple clutch transmission, thereby enablingmultiple shift-stages by a simplified arrangement, improvinginstallability, and reducing an overall weight.

In addition, an exemplary form of the present disclosure may receivetorque from a motor/generator as well as an engine, such that a vehiclemay be driving in an electric vehicle mode and parallel hybrid mode,thereby improving fuel consumption.

Further, effects that can be obtained or expected from exemplary formsof the present disclosure are directly or suggestively described in thefollowing detailed description. That is, various effects expected fromexemplary forms of the present disclosure will be described in thefollowing detailed description.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 is a schematic view of a power transmission apparatus for avehicle according to an exemplary form of the present disclosure; and

FIG. 2 is a shifting operational chart of a power transmission apparatusfor a vehicle according to an exemplary form of the present disclosure.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

As those skilled in the art would realize, the described forms may bemodified in various different ways, all without departing from thespirit or scope of the present disclosure.

In the following description, dividing names of components into first,second and the like is to divide the names because the names of thecomponents are the same as each other and an order thereof is notparticularly limited.

FIG. 1 is a schematic view of a power transmission apparatus for avehicle according to an exemplary form of the present disclosure.

Referring to FIG. 1, a power transmission apparatus shifts torques of anengine ENG as a primary power source and a motor/generator MG as anauxiliary power source, and includes first, second, and third inputshafts IS1, IS2, and IS3, a torque mediating shaft TMS, first and secondintermediate shafts CS1 and CS2, first and second shifting sections TM1and TM2, and an output shaft OS.

The engine ENG is a primary power source and a variety of typicalengines such as a gasoline engine or a diesel engine that uses fossilfuel may be used as the engine ENG.

The motor/generator MG as an auxiliary power source may act as a motorand also as a generator, and includes a stator ST and a rotor RT, wherethe stator ST is fixed to the transmission housing H and the rotor RT isrotatably supported within the stator ST.

Torques from the engine ENG and/or the motor/generator MG are suppliedto the first shifting section TM1, and a plurality of intermediateshift-stages are formed at the first shifting section TM1 by thesupplied torques. Receiving a torque from the first shifting section TM1and selectively receiving a torque from the engine ENG through thesecond input shaft IS2, the second shifting section TM2 performsshifting operation and outputs a shifted torque through the output shaftOS.

The first, second, and third input shafts IS1, IS2, and IS3 and thetorque mediating shaft TMS are disposed on a same axis. The first andsecond intermediate shafts CS1 and CS2 and the output shaft OS aredisposed in parallel with the first input shaft IS1. The secondintermediate shaft CS2 and the output shaft OS are disposed on a sameaxis and selectively interconnected with each other.

The motor/generator MG is disposed to be rear of the engine ENG. A motorshaft MDS fixedly connected with the rotor RT of the motor/generator MGis selectively connected with an output shaft EOS of the engine ENGinterposing an engine clutch ECL.

The first input shaft IS1 is selectively connected with the motor shaftMDS. The first input shaft IS1 delivers torques from the engine ENG andthe motor/generator MG to the first shifting section TM1

The second input shaft IS2 is formed as a hollow shaft and disposedcoaxial with and external to the first input shaft IS1 withoutrotational interference, and selectively connected with the motor shaftMDS thereby selectively transmitting torques of the engine ENG and themotor/generator MG to the second shifting section TM2.

The third input shaft IS3 is formed as a hollow shaft and disposedcoaxial with and external to the second input shaft IS2 withoutrotational interference, and selectively connected with the motor shaftMDS thereby transmitting the torques of the engine ENG and themotor/generator MG to the first shifting section TM1.

The torque mediating shaft TMS is formed as a hollow shaft and disposedcoaxial with and external to the first input shaft IS1.

The second intermediate shaft CS2 is selectively connected with thetransmission housing H through a first brake B1, and may be selectivelyfixed in a rotating direction.

The first shifting section TM1 includes the first and third input shaftsIS1 and IS3, the first and second intermediate shafts CS1 and CS2, andfirst, second, third, fourth, and fifth gear sets GL1, GL2, GL3, GL4,and GL5 disposed on the torque mediating shaft TMS.

The second shifting section TM2 includes a planetary gear set PG. Theplanetary gear set PG is a single pinion planetary gear set, andincludes a sun gear S, a planet carrier PC rotatably supporting aplurality of pinion gears P externally gear-meshed with the sun gear S,and a ring gear R internally gear-meshed with the plurality of piniongears P.

The planetary gear set PG is arranged between the second input shaft IS2and the torque mediating shaft TMS. The sun gear S is fixedly connectedwith the torque mediating shaft TMS. The planet carrier PC is fixedlyconnected with the second input shaft IS2. The ring gear R is externallygear-meshed with the output shaft OS through sixth gear set GL6.

The first gear set GL1 includes a first drive gear IDG1 fixedlyconnected with the third input shaft IS3, and a first driven gear IPG1fixedly connected with the first intermediate shaft CS1 and externallygear-meshed with the first drive gear IDG1.

The second gear set GL2 includes a second drive gear IDG2 rotatablydisposed on an external circumference of the first intermediate shaft CSwithout rotational interference, an intermediate gear ICDG fixedlyconnected with the torque mediating shaft TMS and externally gear-meshedwith the second drive gear IDG2, and a second driven gear IPG2 fixedlyconnected with the second intermediate shaft CS2 and externallygear-meshed with the intermediate gear ICDG.

The third gear set GL3 includes a third drive gear IDG3 fixedlyconnected with the first input shaft IS1, a third driven gear IPG3rotatably disposed on an external circumference of the secondintermediate shaft CS2 without rotational interference and externallygear-meshed with the third drive gear IDG3.

The fourth gear set GL4 includes a fourth drive gear IDG4 fixedlyconnected with the first input shaft IS1, a fourth driven gear IPG4rotatably disposed on an external circumference of the secondintermediate shaft CS2 without rotational interference and externallygear-meshed with the fourth drive gear IDG4.

The fifth gear set GL5 includes a fifth drive gear IDG5 rotatablydisposed on an external circumference of the first intermediate shaftCS1 without rotational interference, and a fifth driven gear IPG5fixedly connected with the second intermediate shaft CS2 and externallygear-meshed with the fifth drive gear IDG5.

The sixth gear set GL6 includes a sixth drive gear IDG6 fixedlyconnected with the ring gear R of the planetary gear set PG, and a sixthdriven gear IPG6 fixedly connected with the output shaft OS andexternally gear-meshed with the sixth drive gear IDG6.

The third driven gear IPG3 and the fourth driven gear IPG4 selectivelyconnected to the second intermediate shaft CS2 by a first synchronizerSN1.

The second drive gear IDG2 and the fifth drive gear IDG5 selectivelyconnected to the first intermediate shaft CS1 by a second synchronizerSN2.

Gear ratios between drive and driven gears of the first, second, third,fourth, and fifth gear sets GL1, GL2, GL3, GL4, GL5, and GL6 may beappropriately set in consideration of transmission requirements. Thegear ratios of the first gear set GL1 and the second gear set GL2 areused for realizing the forward second speed and the forward sixth speed.The gear ratio of the third gear set GL3 is used for realizing theforward first speed and the forward seventh speed. The gear ratio of thefourth gear set GL4 is used for realizing the forward third speed andthe forward fifth speed. The gear ratio of the fifth gear set GL5 isused for realizing the forward ninth speed and the reverse speed incooperation with the gear ratio of the first gear set GL1.

The output shaft OS is an output member, and by receiving torques inputfrom the second intermediate shaft CS2 and from the sixth gear set GL6,transmits the received torque to a differential DIFF through the outputgear OG and the final reduction gear FDG.

In addition, five engagement elements of an engine clutch ECL and firstto fourth clutches CL1, CL2, CL3, and CL4 are disposed between rotatingmembers such as various shafts, and one engagement element of a brake B1is disposed between a rotating member and the transmission housing H.

The engine clutch ECL is arranged between the engine output shaft EOS(e.g., engine crankshaft) and the motor shaft MDS, and selectivelyinterconnects the engine output shaft EOS and the motor shaft MDS.

The first clutch CL1 is arranged between the motor shaft MDS and thefirst input shaft IS1, and selectively connects the motor shaft MDS andthe first input shaft IS1.

The second clutch CL2 is arranged between the motor shaft MDS and thesecond input shaft IS2, and selectively connects the motor shaft MDS andthe second input shaft IS2.

The third clutch CL3 is arranged between the motor shaft MDS and thethird input shaft IS3, and selectively connects the motor shaft MDS andthe third input shaft IS3.

The fourth clutch CL4 is arranged between the second intermediate shaftCS2 and the output shaft OS, and selectively connects the secondintermediate shaft CS2 and the output shaft OS.

The first brake B1 is arranged between the second intermediate shaft CS2and the transmission housing H, and therefore, the second intermediateshaft CS2 and the idle shaft IDS selectively act as fixed elements.

The engagement elements of the engine clutch ECL, the first to fourthclutches CL1 to CL4, and the first brake B1 may be realized asmulti-plate hydraulic pressure friction devices that are frictionallyengaged by hydraulic pressure, however, it should not be understood tobe limited thereto, since various other configuration that areelectrically controllable may be available.

The first and second synchronizers SN1 and SN2 may be formed as a knownscheme, and the first and second sleeves SLE1 and SLE2 applied to thefirst and second synchronizers SN1 and SN2 may be operated by respectiveactuators (not shown) that may be controlled by a transmission controlunit.

According to one form, the second shifting section TM2 is disposed at arear side of the engine ENG, and the first shifting section TM1 isdisposed at a rear side of the second shifting section TM2.

FIG. 2 is a shifting operational chart for a power transmissionapparatus for a vehicle according to an exemplary form of the presentdisclosure, and the power transmission apparatus for a vehicle accordingto an exemplary form performs shifting operation as follows.

[Engine and Parallel Mode Reverse Speed]

In the engine and parallel mode reverse speed REV, as shown in FIG. 2,the fifth drive gear IDG5 is synchronously connected to the firstintermediate shaft CS1 by the operation of the sleeve SLE2 of the secondsynchronizer SN2, and the engine clutch ECL and the third and fourthclutches CL3 and CL4 are operated.

As a result, by the operation of the engine clutch ECL, the third clutchCL3 and the second synchronizer SN2, the torque of the engine ENG isinput to the second intermediate shaft CS2 through the motor shaft MDS,the third input shaft IS3, the first gear set GL1, the secondsynchronizer SN2, the first intermediate shaft CS1, and the fifth gearset GL5.

Then, the torque received at the second intermediate shaft CS2 istransmitted to the differential DIFF through the output shaft OS by theoperation of the fourth clutch CL4, thereby realizing the reverse speed.

[The Engine and Parallel Mode Forward First Speed]

In the engine and parallel mode forward first speed FD1, as shown inFIG. 2, the third driven gear IPG3 is synchronously connected to thesecond intermediate shaft CS2 by the operation of the sleeve SLE1 of thefirst synchronizer SN1, and the engine clutch ECL and the first, fourthclutch CL1 and CL4 are operated.

As a result, by the operation of the engine clutch ECL, the first clutchCL1, and the first synchronizer SN1, the torque of the engine ENG istransmitted to the second intermediate shaft CS2 through the motor shaftMDS, the first input shaft IS1, the third gear set GL3, and the firstsynchronizer SN1.

Then, the torque received at the second intermediate shaft CS2 istransmitted to the differential DIFF through the output shaft OS by theoperation of the fourth clutch CL4, thereby realizing the forward firstspeed.

[The Engine and Parallel Mode Forward Second Speed]

In the engine and parallel mode forward second speed FD2, as shown inFIG. 2, the second drive gear IDG2 is synchronously connected to thefirst intermediate shaft CS1 by the operation of the sleeve SLE2 of thesecond synchronizer SN2, and the engine clutch ECL and the third andfourth clutches CL3 and CL4 are operated.

As a result, by the operation of the engine clutch ECL, the third clutchCL3 and the second synchronizer SN2, the torque of the engine ENG isinput to the second intermediate shaft CS2 through the motor shaft MDS,the third input shaft IS3, the first gear set GL1, the secondsynchronizer SN2, the first intermediate shaft CS1, and the second gearset GL2.

Then, the torque received at the second intermediate shaft CS2 istransmitted to the differential DIFF through the output shaft OS by theoperation of the fourth clutch CL4, thereby realizing the forward secondspeed.

[The Engine and Parallel Mode Forward Third Speed]

In the engine and parallel mode forward third speed FD3, as shown inFIG. 2, the fourth driven gear IPG4 is synchronously connected to thesecond intermediate shaft CS2 by the operation of the sleeve SLE1 of thefirst synchronizer SN1, and the engine clutch ECL and the first, fourthclutch CL1 and CL4 are operated.

As a result, by the operation of the engine clutch ECL, the first clutchCL1, and the first synchronizer SN1, the torque of the engine ENG istransmitted to the second intermediate shaft CS2 through the motor shaftMDS, the first input shaft IS1, the fourth gear set GL4, and the firstsynchronizer SN1.

Then, the torque received at the second intermediate shaft CS2 istransmitted to the differential DIFF through the output shaft OS by theoperation of the fourth clutch CL4, thereby realizing the forward thirdspeed.

[The Engine and Parallel Mode Forward Fourth Speed]

In the engine and parallel mode forward fourth speed FD4, as shown inFIG. 2, the first and second synchronizers SN1 and SN2 are maintainedneutral, and the engine clutch ECL and the second, fourth clutch CL2 andCL4 are operated.

As a result, by the operation of the engine clutch ECL and the secondclutch CL2, the torque of the engine ENG is input to the planet carrierPC of the planetary gear set PG through the motor shaft MDS and thesecond input shaft IS2.

By the operation of the fourth clutch CL4, the sixth gear set GL6, theoutput shaft OS, the second intermediate shaft CS2, the second gear setGL2, and the torque mediating shaft TMS are interconnected, and therebythe ring gear R connected to the sixth gear set GL6 is connected withthe sun gear S connected to the torque mediating shaft TMS. The speedrelation between the ring gear R and the sun gear S is formed by thegear ratios of the second and sixth gear sets GL2 and GL6, while theplanet carrier PC of the planetary gear set PG receives an input torquethrough the second input shaft IS2. Therefore, the sun gear S and thering gear R of the planetary gear set PG rotate at respective speedssatisfying the speed relation while the planet carrier PC rotates at thespeed of the second input shaft IS2.

By such a cooperative operation of rotation members of the planetarygear PG, the speed and torque of the output shaft OS connected to thesixth gear set GL6 is determined and transmitted to the differentialDIFF through the output shaft OS, thereby realizing the forward fourthspeed.

[The Engine and Parallel Mode Forward Fifth Speed]

In the engine and parallel mode forward fifth speed FD5, as shown inFIG. 2, the fourth driven gear IPG4 is synchronously connected to thesecond intermediate shaft CS2 by the operation of the sleeve SLE1 of thefirst synchronizer SN1, and the engine clutch ECL and the first andsecond clutches CL1 and CL2 are operated.

As a result, by the operation of the engine clutch ECL, the first clutchCL1, and the first synchronizer SN1, the torque of the engine ENG ispartially input to the sun gear S of the planetary gear set PG throughthe motor shaft MDS, the first input shaft IS1, the fourth gear set GL4,the first synchronizer SN1, the second intermediate shaft CS2, and thesecond gear set GL2.

In addition, by the operation of the second clutch CL2, the torque ofthe engine ENG is partially input to the planet carrier PC of theplanetary gear set PG through the motor shaft MDS and the second inputshaft IS2.

Then, the planetary gear set PG realizes shifting based on speeddifference between the sun gear S and the planet carrier PC, and outputsthe shifted torque to the differential DIFF through the output shaft OS,thereby realizing the forward fifth speed.

[The Engine and Parallel Mode Forward Sixth Speed]

In the engine and parallel mode forward sixth speed FD6, as shown inFIG. 2, the second drive gear IDG2 is synchronously connected to thefirst intermediate shaft CS1 by the operation of the sleeve SLE2 of thesecond synchronizer SN2, and the engine clutch ECL and the second andthird clutches CL2 and CL3 are operated.

As a result, by the operation of the engine clutch ECL and the secondclutch CL2, the torque of the engine ENG is partially input to theplanet carrier PC of the planetary gear set PG through the motor shaftMDS and the second input shaft IS2.

In addition, by the operation of the third clutch CL3 and the secondsynchronizer SN2, the torque of the engine ENG is partially input to thesun gear S of the planetary gear set PG through the motor shaft MDS, thethird input shaft IS3, the first gear set GL1, the second synchronizerSN2, the first intermediate shaft CS1, and the second gear set GL2.

Then, the planetary gear set PG realizes shifting based on speeddifference between the sun gear S and the planet carrier PC, and outputsthe shifted torque to the differential DIFF through the output shaft OS,thereby realizing the forward sixth speed.

[The Engine and Parallel Mode Forward Seventh Speed]

In the engine and parallel mode forward seventh speed FD7, as shown inFIG. 2, the third driven gear IPG3 is synchronously connected to thesecond intermediate shaft CS2 by the operation of the sleeve SLE1 of thefirst synchronizer SN1, and the engine clutch ECL and the first andsecond clutches CL1 and CL2 are operated.

As a result, by the operation of the engine clutch ECL, the first clutchCL1, and the first synchronizer SN1, the torque of the engine ENG ispartially input to the sun gear S of the planetary gear set PG throughthe motor shaft MDS, the first input shaft IS1, the third gear set GL3,the and the first synchronizer SN1, the second intermediate shaft OS2,and the second gear set GL2, torque mediating shaft TMS.

In addition, by the operation of the second clutch CL2, the torque ofthe engine ENG is partially input to the planet carrier PC of theplanetary gear set PG through the motor shaft MDS and the second inputshaft IS2.

Then, the planetary gear set PG realizes shifting based on speeddifference between the sun gear S and the planet carrier PC, and outputsthe shifted torque to the differential DIFF through the output shaft OS,thereby realizing the forward seventh speed.

[The Engine and Parallel Mode Forward Eighth Speed]

In the engine and parallel mode forward eighth speed FD8, as shown inFIG. 2, the first and second synchronizers SN1 and SN2 are maintainedneutral, and the engine clutch ECL, the second clutch CL2, and the firstbrake B1 are operated.

As a result, by the operation of the engine clutch ECL and second clutchCL2, the torque of the engine ENG is input to the planet carrier PC ofthe planetary gear set PG through the motor shaft MDS and the secondinput shaft IS2, and by the operation of the first brake B1, the sungear S of the planetary gear set PG acts as a fixed element.

Then, since the planet carrier PC of the planetary gear set planetarygear set PG receives input torque while the sun gear S acts as a fixedelement, the planetary gear set planetary gear set PG outputs anincreased speed through the ring gear R, and the torque output throughthe ring gear R is transmitted to the differential DIFF through thesixth gear set GL6 and the output shaft OS, thereby realizing theforward eighth speed.

In such a forward eighth speed, the planetary gear set PG outputs afurther increased speed than in the forward seventh speed.

[The Engine and Parallel Mode Forward Ninth Speed]

In the engine and parallel mode forward ninth speed FD9, as shown inFIG. 2, the fifth drive gear IDG5 is synchronously connected to thefirst intermediate shaft CS1 by the operation of the sleeve SLE2 of thesecond synchronizer SN2, and the engine clutch ECL and the second andthird clutches CL2 and CL3 are operated.

As a result, by the operation of the engine clutch ECL and the secondclutch CL2, the torque of the engine ENG is partially input to theplanet carrier PC of the planetary gear set PG through the motor shaftMDS and the second input shaft IS2.

In addition, by the operation of the third clutch CL3, the torque of theengine ENG is partially input to the sun gear S of the planetary gearset PG through the motor shaft MDS, the third input shaft IS3, the firstgear set GL1, the first intermediate shaft CS1, the second synchronizerSN2, the fourth gear set GL5, the second intermediate shaft CS2, and thesecond gear set GL2.

Then, the planetary gear set PG outputs a further increased speed thanin the forward eighth speed through the ring gear R, and the torqueoutput through the ring gear R is transmitted to the differential DIFFthrough the sixth gear set GL6 and the output shaft OS, therebyrealizing the forward ninth speed.

In such a forward ninth speed, the planetary gear set PG outputs afurther increased speed than in the forward eighth speed.

In the above description of the “engine and parallel mode”, only theengine ENG is exampled as a power source. However, it may be obviouslyunderstood that such shifting operation may be maintained even if themotor/generator MG is activated to form a parallel mode and assist theengine ENG.

An electric vehicle mode EV mode differs from the engine and parallelmode, only in that the engine ENG is stopped while releasing the engineclutch ECL and only the motor/generator MG is used as sole power source.It may be understood that such a difference will not affect theabove-described shifting operation, and thus, in such an electricvehicle mode EV mode the same shift-stages of one reverse speed REV andnine forward speeds of the forward first speed FD1 to the forward ninthspeed FD9 may be obtained by the same operational chart.

A power transmission apparatus for a vehicle according to an exemplaryform of the present disclosure realizes shift-stages of nine forwardspeeds and one reverse speed by employing a planetary gear set and twosynchronizers to a multiple clutch transmission, thereby enablingmultiple shift-stages by a simplified arrangement, improvinginstallability, and reducing an overall weight.

In addition, an exemplary form of the present disclosure may receivetorque from a motor/generator as well as an engine, such that a vehiclemay be driving in an electric vehicle mode and parallel hybrid mode,thereby improving fuel consumption.

While this present disclosure has been described in connection with whatis presently considered to be practical exemplary forms, it is to beunderstood that the present disclosure is not limited to the disclosedforms, but, on the contrary, is intended to cover various modificationsand equivalent arrangements included within the spirit and scope of thepresent disclosure.

DESCRIPTION OF SYMBOLS

-   -   B1: first brake    -   CL1, CL2, CL3, CL4: first, second, third, and fourth clutches    -   CS1, CS2: first and second intermediate shafts    -   ECL: engine clutch    -   EOS: engine output shaft (crankshaft)    -   GL1, GL2, GL3, GL4, GL5, GL6: first, second, third, fourth,        fifth, and sixth gear sets    -   ICDG: intermediate gear    -   IDG1, IDG2, IDG3, IDG4, IDG5, IDG6: first, second, third,        fourth, fifth, and sixth drive gears    -   IPG1, IPG2, IPG3, IPG4, IPG5, IPG6: first, second, third,        fourth, fifth, and sixth driven gears    -   IS1, IS2, IS3: first, second, and third input shafts    -   MDS: motor shaft    -   OG: output gear    -   OS: output shaft    -   PG: planetary gear set    -   SN1, SN2: first and second synchronizers    -   TMS: torque mediating shaft    -   TM1, TM2: first and second shifting sections

What is claimed is:
 1. A power transmission apparatus for a vehiclehaving an engine and a motor/generator, the power transmission apparatuscomprising: a first input shaft selectively connected with themotor/generator; a second input shaft formed as a hollow shaft, disposedcoaxially with and external to the first input shaft without rotationalinterference, and selectively connected with the motor/generator; athird input shaft formed as a hollow shaft, disposed coaxially with andexternal to the second input shaft without rotational interference, andselectively connected with the motor/generator; a torque mediating shaftformed as a hollow shaft disposed coaxially with and external to thefirst input shaft without rotational interference; a first intermediateshaft disposed in parallel with the first input shaft; a secondintermediate shaft disposed in parallel with the first input shaft, andselectively connected with a transmission housing; a first shiftingsection including a first gear set, a second gear set, a third gear set,a fourth gear set, and a fifth gear set, each of which is disposed on atleast one corresponding shaft among the first input shaft, the thirdinput shaft, the first intermediate shaft, the second intermediateshaft, and the torque mediating shaft, where the first shifting sectionis configured to selectively receive a first torque through the firstand third input shafts and to provide a plurality of intermediateshift-stages shifted from the received first torque; a second shiftingsection including a planetary gear set having a sun gear fixedlyconnected with the torque mediating shaft, forming an output torque bycombination of a second torque selectively transmitted from the firstshifting section and a third torque selectively input through the secondinput shaft, the second shifting section configured to output the outputtorque to an output shaft through one gear set selected among the first,second, third, fourth and fifth gear sets of the first shifting section;and wherein the output shaft is disposed coaxially with and selectivelyconnected with the second intermediate shaft and outputs a fourth torquereceived from the first and second shifting sections.
 2. The powertransmission apparatus of claim 1, wherein the first gear set includes:a first drive gear fixedly connected with the third input shaft; and afirst driven gear fixedly connected with the first intermediate shaftand externally gear-meshed with the first drive gear, wherein the secondgear set includes: a second drive gear disposed coaxial with andexternal to the first intermediate shaft without rotationalinterference; an intermediate gear fixedly connected with the torquemediating shaft and externally gear-meshed with the second drive gear;and a second driven gear fixedly connected with the second intermediateshaft and externally gear-meshed with the intermediate gear, wherein thethird gear set includes: a third drive gear fixedly connected with thefirst input shaft; and a third driven gear rotatably disposed on anexternal circumference of the second intermediate shaft withoutrotational interference and externally gear-meshed with the third drivegear, wherein the fourth gear set includes: a fourth drive gear fixedlyconnected with the first input shaft; and a fourth driven gear rotatablydisposed on an external circumference of the second intermediate shaftwithout rotational interference and externally gear-meshed with thefourth drive gear, and wherein the fifth gear set includes: a fifthdrive gear disposed coaxial with and external to the first intermediateshaft without rotational interference; and a fifth driven gear fixedlyconnected with the second intermediate shaft and externally gear-meshedwith the fifth drive gear.
 3. The power transmission apparatus of claim2, wherein: the third driven gear and the fourth driven gear areselectively connected with the second intermediate shaft through a firstsynchronizer; and the second drive gear and the fifth drive gear areselectively connected with the first intermediate shaft through a secondsynchronizer.
 4. The power transmission apparatus of claim 2, wherein:gear ratios of the first gear set and the second gear set are configuredto provide a forward second speed and a forward sixth speed; a gearratio of the third gear set is configured to provide a forward firstspeed and a forward seventh speed; a gear ratio of the fourth gear setis configured to provide a forward third speed and a forward fifthspeed; and a gear ratio of the fifth gear set is configured to provide aforward ninth speed and a reverse speed in cooperation with the gearratio of the first gear set.
 5. The power transmission apparatus ofclaim 1, wherein: the sun gear of the planetary gear set is fixedlyconnected with the torque mediating shaft; a planet carrier of theplanetary gear set is fixedly connected with the second input shaft; anda ring gear of the planetary gear set is externally gear-meshed with theoutput shaft through a sixth gear set.
 6. The power transmissionapparatus of claim 5, wherein the sixth gear set comprises: a sixthdrive gear fixedly connected with the ring gear of the planetary gearset; and a sixth driven gear fixedly connected with the output shaft andexternally gear-meshed with the sixth drive gear.
 7. The powertransmission apparatus of claim 5, wherein the planetary gear set is asingle pinion planetary gear set.
 8. The power transmission apparatus ofclaim 1, further comprising: five clutches each selectively connecting acorresponding pair among the first, second and third input shafts, thetorque mediating shaft, and the first and second intermediate shafts;and a brake selectively connecting a corresponding shaft selected amongthe first, second and third input shafts, the torque mediating shaft,and the first and second intermediate shafts to the transmissionhousing.
 9. The power transmission apparatus of claim 8, wherein thefive clutches comprise: an engine clutch arranged between an engineoutput shaft of the engine and a motor shaft of the motor/generator; afirst clutch arranged between the motor shaft and the first input shaft;a second clutch arranged between the motor shaft and the second inputshaft; a third clutch arranged between the motor shaft and the thirdinput shaft; and a fourth clutch arranged between the secondintermediate shaft and the output shaft, wherein the brake is arrangedbetween the second intermediate shaft and the transmission housing. 10.The power transmission apparatus of claim 1, wherein the second shiftingsection is disposed closer to the engine than the second, third, fourth,and fifth gear sets of the first shifting section.